Mahou Sensou: Lost In Dimension
by Shidou Haruka
Summary: Mahou Sensou AU after LN vol 7. In order to find a way back to the future, Takeshi asks Shijou Momoka for help. On the day of his return journey, the spell that would help him go back went wrong and Takeshi along with Sophia and Momoka is thrown into another world. Can the three magicians survive the world where Angels, Fallen Angels, and Devils live?
1. Chapter 1

**Life 1: A Mistake In Calculation**

-Phoenix Foundation, Brave Mansion-

Three teens are gathered inside Sophia Brave's room in the Brave mansion. It is Sophia's usual group of friends which consists of who she claims to be two of her most beloved people in the world, Nanase Takeshi and Shijou Momoka. One is her destined person and the other is her best friend. It's not clear for the two subjects in question why she claims that but her Ancestral Magic is not really easy to understand.

The three of them are currently discussing something, it is about Takeshi. Nanase Takeshi is someone who came from the future due to a large explosion of magic that could bend space and time. After almost two years of being stuck in the past, Takeshi finally found a lead to how he can go back home to his own time.

"Hmm, theoretically it should be possible but…"

"But what, Momo-tan?"

"Uhh… it's extremely complicated. I know that it was the future me that sent Nanase-kun back to the past but I don't have the experience and knowledge of the future me."

Momoka brought up a fine point. They had figured out that only Momoka's Ancestral Magic could've sent Takeshi back in time due to its property. But to reverse the process through this timeline's Momoka is extremely hard. For one, the Momoka in the future has decades of experience and accumulated knowledge and her power had reached its peak. The current Momoka doesn't have all that and can't possibly send him back to the future, not yet.

"Can't anything be done?"

Takeshi asked. It's been two years and he's feeling anxious. A war broke out in his timeline and he needs to return. He can't just let his friends fight the war alone. But there is also another problem, one that makes it much more complicated than just time-travelling.

"Well, the time part can be done if we're talking about linear timeline but… Since we're not sending you straight to the future but a parallel future it makes things more complicated."

Yes, Takeshi was not only sent back to the past but to a parallel dimension. In this world, Ryuusenji Kazuma was not a magician and therefore Ghost Trailer never came to be. It was a mistake in calculation. If he was sent to his world's past, he could understand that he was supposed to do something about the future. But the future Momoka's mistake in calculation sent him not just to the past but to a parallel dimension.

Ghost Trailer does not exist in this dimension and there is peace. For two years he stayed with the Brave family thanks to Sophia who knew of his plight due to her Magical Analysis, her Ancestral Magic. He trained for two years straight in preparation for returning to his timeline and he's ready. The problem is, Momoka is not ready.

"Sending someone to the future is much more complicated than sending someone to the past. To send someone to the past we just need to displace them from their time and then place them into a known time. Of course, this is a simplified explanation. An analogy would be moving a book from one shelf to another shelf. You're putting it into something that already has a precedence and it exists. But sending someone to the future is like trying to put the same book into a shelf that is yet to be built. You don't know how it looks and there is nothing to place it on. And it's worse because not only are we going to send him to the future but also to a parallel timeline. This is not the case of the shelf not existing but you're trying to put the book into an inexistent shelf in another house!"

Momoka explained. It's frustrating really, and they have to do it because Takeshi is a key part of the war in his timeline if he's chosen by Momoka of that timeline to go back to the past. Momoka thought for a while. She cannot do both process of sending him to a parallel timeline and to the future all at once. She can either send him to the future or send him to a parallel timeline. Doing both is impossible… unless.

"…there is one, but much more complicated and roundabout way though."

"There is a way?"

Momoka nodded. She had not thought of it before and it is a crazy idea but it is the best they have.

"I cannot do both process of placing you in the right timeline and then send you to the future all at once. But I don't have to. I need to send you to a parallel timeline, one that will connect to your future, and then you can have that version of me send you to the future."

"Yes! That could work! Momo-tan is so smart!"

Sophia exclaimed while patting Momoka on her head. The chibi girl doesn't look too happy being pat on the head because she doesn't like being treated like a kid (even though she's one) but Sophia is the sole exception.

Although the solution is not perfect, Takeshi could accept it. After all, it's the best they have and possibly the only one they will ever have. He's already asking for so much from the two of them. The roundabout way is better than nothing at all. But… Takeshi stole a glance at Sophia who is laughing merrily as she glomped Momoka like she's a teddy bear. He knew that she is sad that Takeshi won't be staying. She really likes him from the first time they met and she has also grown on him in the two years he stayed in the Brave mansion.

Even if he already has Isoshima Kurumi, Sophia Brave had wormed her way into his heart and will forever be someone he cannot forget. Of course, the same goes for Momoka though in the chibi's case she is more like a mentor despite the difference in age… in both cases. He first met her in his future timeline when he gained the power to be a magician and she welcomed him to Subaru Magic Academy as its headmaster.

That Shijou Momoka is always cool, mysterious, knowledgeable, and has an air of authority and power, a truly high-class magician that could stand equally to Ghost Trailer's second-in-command. But this Momoka is, although also knowledgeable, is also much more relaxed, more expressive, and… sometimes childish. She feels more like a real teenage girl than the headmistress he had come to know.

He'll miss them once he got back to his time. It's going to be different. Even if he could meet Momoka again, the headmistress he knew is not the girl who is currently being annoyed by her best friend. And the Sophia he will meet won't be the same Sophia that he now knew. Even a part of him doesn't want to go back because all he will find is war while here he can live in peace with his two friends.

But Takeshi cannot abandon his friends. That's why he must go back, even if he has to take the long way around, if it is the only way then so be it. But that doesn't mean he won't feel a hint of regret.

* * *

-3 months later-

Momoka made sure that everything is perfect. There can be no mistake. She had spent the last year studying for this moment. This will be her greatest test, to help her friend return to his timeline. She's still far from being able to influence 'time' using her magic at her current level but she had switched her focus specifically to 'space' in the last three months and with a clear objective in mind, she is sure that she will succeed.

And today will be the day when she will see whether she succeeded or not.

The trio are now in Sophia's workshop. They had cleared the room in order to perform this magnificent piece of magic. After all, sending someone to a parallel world is a big feat, especially if it is their friend.

Takeshi is wearing his Wizard Brace uniform like Momoka while Sophia is wearing her Phoenix Foundation robe. The three of them stood in a circle around two meters apart from each other. Twilight is sheathed on Takeshi's waist lying dormant until it is called to battle. The only one with her Aspect active is Momoka. The enormous compass that towers over its own wielder stood ready in preparation.

"Nanase-kun, are you ready?"

The chibi girl asked. Takeshi nodded. He is ready. Once Momoka opened up a gate, there will be no turning back. Momoka cast a discreet glance at Sophia but the read head did not respond. Momoka took this as a sign that she had come to terms with Takeshi leaving. With nothing more need to be said, Momoka began her spell. She throws her Compass to the air and when it floats right above their head she began to chant.

" _The road towards the night has revealed itself. The door to the endless void shall open. The journey starts with a single step, Black Arc!_ "

Her compass began to spin like a propeller and a black magic circle appear under it. From the magic circle, a pillar of black light shot down.

This is the magic that Momoka had been working on, a gate to another world. She had spent a lot of her time just to construct this spell and learn things beyond her age. This is truly the work of a prodigy. By entering this pillar of black light, Takeshi can be on his way back to his world one step at a time. first is to reach his timeline's correct past and from there, back to the future. Takeshi stepped forward with his face now inches away from the pillar of black light.

"I guess this is it. This is goodbye."

Takeshi said to Sophia. But the girl didn't reply. Her eyes are fixed on the pillar of light as if she's in a trance. Takeshi noticed her eyes. Her Ancestral Magic is active and her eyes suddenly widen.

"Takeshi, Momo-tan, get away!"

"Huh?!"

"No! There's a mistake in calculation?! No, this is outside interference!"

Suddenly the power of the magic increase several fold. The pillar of light began to expand, engulfing not only Takeshi but also Momoka and Sophia. Once the light disappeared, all three of them can no longer be seen. They have disappeared forever into the void… or did they?

* * *

-Unknown location-

Takeshi landed face first on the ground. He groaned as he tries to stand up. But the poor boy cannot stand up because a moment later Sophia and Momoka both landed on him.

"Uwaa! Takeshi, are you alright?!"

Sophia immediately got up along with Momoka. Takeshi groaned louder and tries to stand up again while holding his back which is currently in pain. Sophia helped him up while Momoka look around.

"Ugh, what happened?"

Takeshi asked as he is probably the only one who has no idea what happened. Momoka as the caster must knew about something while Sophia has her Magical Analysis.

"We failed… and succeed at the same time."

"Something interfered with the spell. I… I saw a large red dragon with four wings looking straight at us."

"A red dragon?"

Sophia won't forget what she saw. A giant red dragon larger than anything she had ever seen radiating an unbelievable amount of power. It had stared back at her and it had interfered with Momoka's magic. She had never seen anything like it and she probably never will again.

"So, where are we?"

The answer to Takeshi's question came not from any of his companion but a new voice.

"Well well well, what have we here?"

The three of them turn around to the source of that voice and cannot believe what they are seeing. A man is floating above them. He has a black hair with a mix of blonde and a small goatee. He looks to be middle-aged but none of those features matters more than what he has on his back.

Twelve feathery wings as dark as the night itself suspends the man in the air. He is the very image of what one would call a Fallen Angel.

"So, what are you three doing in Grigori territory?"

* * *

 **So I was reviewing about what I did in my Mikazuki of the Requiem story and decided to scrap that thing and do a legit Mahou Sensou crossover (at last!) after using the series' characters too many times. For those who only watch the anime, this takes place in an alternate version of Light Novel volume 7 and beyond. Which means this one is after the anime. Sophia Brave is a real Mahou Sensou character that appears in LN volume 7.**

 **So the main character this time is Takeshi and with him is Sophia Brave and Subaru Mahou Gakuen's principal Shijou Momoka... when she was much younger. In volume 7 Momoka is just around 12 years old. Though her skill is unquestionable if she can match Kippei.**

 **This is around 1 and a half year before canon timeline starts. There's a reason for that, mostly for Sophia's sake. Anyway, I hope this one is better than my previous Mahou Sensou attempt.**


	2. Chapter 2

**Life 2: Adjusting**

It has been three months since the magicians were taken in by Grigori. Knowing the importance of having an ally in an unknown world, Momoka decided to explain what happened truthfully. Thankfully, the fallen angel that found them is the leader of Grigori, Azazel, and he is an… interesting person to put it politely.

In the three months since their arrival, they have been staying in Azazel's house. The fallen angel had been having a blast learning about new kind of magic and knowledge from another world in exchange for him providing them a place to live and knowledge, mostly utilized by Momoka since she's the scholar of the three.

They found out that human magician exists in this world but unlike in their world, there is no such thing as ancestral magic that belongs only to specific magicians and their system of magic is rather different but not extremely so that they can't learn it. In fact, in the span of three months, Momoka managed to grasp the basic of magic of the new world and some of the intermediate ones. Then again, she's a prodigy that even Azazel acknowledged.

Sophia will follow Momoka in studying this world's magic. She's also interested and she could increase her spell repertoire since this world is dangerous according to Azazel and she's limited in her combat spells since she's originally not a combat magician but a craftsman. Although not as talented as Momoka, Sophia is smart and she managed to learn this world's magic at a fast rate and prove herself to be more than above average magician.

Takeshi though is different from his companions. Unlike them who expand their magic repertoire with new spells, Takeshi learns very few new spells. Instead he focuses on physical training and swordsmanship. Takeshi who is already a very formidable swordsman had only improved further after training under Ikuse Tobio, the Slash Dog of Grigori.

All three of them interests Azazel. After all, you don't get a visitor from another world very often. Hell, it might take several thousand years for it to happen again and that might just be wishful thinking.

The trio of magician continue their training and study in Grigori through the season and then as spring entered its second week, Azazel called all three of them to his study telling them that he has a surprise for them. The three magicians, not knowing what the Governor of Grigori wants, entered his study.

"So what do you need us for, Azazel?"

Momoka was the first one to ask without even addressing him with respect being the one closest to him among the three due to her helping said Governor in his lab, a lot. Due to that, she had actually lost all respect to the man. Azazel grinned and showed them some papers. The three magicians wondered what it is and took one each.

"This is… a transfer paper?"

Takeshi tilted his head, not understanding why he is showing them a school transfer paper… until he saw his name on it.

"What?!"

Momoka was the first to react and the loudest. She look between the paper and the grinning Azazel and soon a tick mark appear on her forehead.

"What is the meaning of this?!"

She demanded as Takeshi nodded in agreement. They didn't hear anything about this.

"Well you see, I figured you guys will get bored if you just stay in this house or visit Grigori so I thought why not let you guys experience what this world has to offer?"

Azazel calmly replied despite the glare Momoka send him that could've made lesser men cower in fear. Momoka is certainly not very happy about this, especially since they weren't informed about going to any school. Takeshi though has a different problem with the arrangement.

"Umm, Azazel-san, the paper said that I will be placed in high school as a second year student."

"Is there any problem there?"

Azazel asked, not really seeing the problem. Actually, it's not much of a problem except for one small detail. Takeshi and Sophia are eighteen years old and almost reaching nineteen which should make them a college freshman instead of highschool student.

"Well…"

"You wouldn't want to leave your young friend in highschool alone, would you?"

Azazel gestured at the youngest magician of the three. The prodigy herself is glaring at him, totally annoyed. Takeshi took a peek at Momoka's paper and saw that she's also placed as a second year highschool student although in her case, her age makes her too young to be one but her brain definitely isn't.

Before Momoka and Takeshi could protest though, the third magician who has been silent all this time grab their hands and with sparkling eyes told them in her usual excited manner.

"Let's go to this school! Ahh, I never thought that I could experience this. Hey Momo-tan, Takeshi, let's go to school together! I have always wanted to go to school with my best friends! Let's go!"

Any objection to the idea was immediately forgotten when Sophia Brave pulled them into an excited hug and they knew she wouldn't take no for an answer. Azazel smiled. With Sophia welcome to the idea, he knew he finally got them. He knew that the two of them kind of dotes on Sophia. Momoka and Takeshi rarely say no to her and when she gets like this, they would easily accept their fate.

With Sophia Brave on board with the idea, Takeshi and Momoka resigned themselves to just packing their bags and go along with the whole thing. Who knows, like Sophia said, it could be fun.

* * *

In just three days they were shipped off to Kuoh and both Takeshi and Momoka are not in a good mood, especially Momoka, and it all started because Azazel neglect to mention a very important piece of information until they're about to leave.

Kuoh is devil territory and the school they're going to is basically run by devils.

Momoka would've throttled Azazel there and then if he hadn't teleported away immediately. The little prodigy had developed quite the temper after working with Azazel for several months. Takeshi had known Momoka for more than two years now and he had never seen her easily lost her cool like with Azazel. She is usually always calm and collected, whether it is this version that he had come to know or the version who is the headmistress of Subaru Magic Academy. He had to admit though that Azazel really could get on someone's nerves.

The only one among them who doesn't seem to care is Sophia who is currently clinging to his arm while humming happily. They look like a happy couple going to school together and they might as well be. Takeshi still doesn't know where he stands in this relationship. Sophia has always been like this and he just kind of accept it. But there is still Kurumi back in his homeworld and he knows he still love her. But he knows that he and Sophia are more than just friends.

He tries not to think too much about it because it is confusing him. But eventually, he knew he has to make a decision, one that he will not regret. But for now, he will let things run its course. He can't do much more than that anyway. Whether he like it or not, Momoka is the one doing all the work for them because she's the only one who can. Sometimes he hope that he could help the young prodigy in finding their way home but unfortunately he is just not able to.

Said prodigy is currently walking in front of them and he could hear her muttering things that shouldn't be said by someone her age. Takeshi shivers. Momoka is scary when she wants to be. He really doesn't want to cross her, especially knowing the amount of power she possess and the might of her Ancestral Magic.

When the trio arrive in front of the school, they began to hear whispering, most of it aimed at Takeshi who has Sophia clinging to him. Right then, Takeshi knew that it will be a very long school year… incidentally, everyone also seem to open a path for them when they felt Momoka approaching. She still hasn't calm down yet and everyone is wise enough to stay out of her way.

"You two, stop your lovey-dovey act and let's get to the faculty office!"

Momoka yelled at them. Sophia pouted and let go of Takeshi and the two fell into line with Momoka. Takeshi simply hoped that she would calm down soon and again hoped that nobody is at Azazel's level when it comes to annoying her.

* * *

Fortunately, Momoka had calmed down after their visit to the faculty room and talking with their homeroom teacher about their transfer. Azazel at least made sure that everything was okay before sending them off. Say what you may about his attitude but when he does a job he does it right.

Now all three of them are standing in front of their class for introduction. Takeshi is feeling a little nervous since it's a new school and a new class and fortunately for him, the introduction doesn't start with him but with Momoka.

"I'm Shijou Momoka. I like studying and I hate people who bothers me. That's all."

That's too short and straight to the point! Although she had calmed down, Momoka is still feeling a little irritated with Azazel.. Before the ball can be passed to Takeshi's court, someone raised a hand.

"Umm, Shijou-san, are you actually… you don't look… you know."

A girl at the back of the class asked. It seems she has trouble voicing what she's thinking although Takeshi could guess what she's asking. Momoka sighs. Someone would eventually ask anyway since she doesn't look like a highschool student.

"I'm fourteen. I skipped grades."

""Ehh!""

Everyone is surprised by her admittance. She's younger than them by approximately two years! It's rare to see a prodigy like her so their reaction is understandable.

"Alright, enough of that. Please treat Shijou-san like any of your other classmate even if she's younger. Try to behave yourselves and I don't want to hear about any bullying, okay?"

The teacher told them. True, bullying might be a problem when you have a young prodigy among you but Takeshi doubt that anyone can bully Momoka. They can try but it certainly won't end well for them. Finally, it's time for Takeshi to introduce himself. He wrote his name in kanji beside Momoka's own and turn to face the class.

"My name is Nanase Takeshi. I practice kendo and I like training. It's nice to meet you all."

Takeshi politely bowed. Some girls began whispering to each other while the guys are muttering something he can't really hear. Another thing that he didn't notice is the red haired girl beside him is no longer smiling but pouting. Once Takeshi finished his introduction, it's Sophia's turn. She write her name on the blackboard and unlike her two friends, she write her name all in katakana because she's not a Japanese native.

"My name is Sophia Brave and I'm warning all of you hussy to stay away from Takeshi! He's mine!"

Sophia declared as she again cling on to Takeshi's arm. Momoka sighs once again while Takeshi was caught off guard by her declaration. After that, the class descends into chaos.

* * *

 **It's been a while. Anyway, I haven't forgotten about this story. I just didn't have anything for the plot until now. So Azazel has agents in Kuoh much more competent than Raynare. What will happen now that the magician trio arrived? Nothing much yet since this is only the beginning. Anyway, I'm thinking a little bit about pairing. The default pairing would be Takeshi x Sophia but should I make it a harem or not?**

 **Zerodragon: I hope someone would translate it. although I've read it and collected the whole LN series after the anime, I still have trouble reading full japanse though I do get most of it. Sophia is awesome. You should read the LN.**


End file.
